Powered underwater motive devices have been known since the 1950's. Most of those earlier devices were metal and were built like small submarines. Access was had through hatches which had to be securely bolted or clamped in order to resist taking on water at depth. Water is harmful to both motors and batteries and must be sealed out. As a result, the underwater motive devices were large, bulky and designed with a mind to limit outside access to limit the sealing areas provided for service access.
Recent improvements in underwater motive devices have related to the safety of operation, including a slight delay in starting to prevent inadvertent operation. In addition, sealed chambers have been introduced to keep water out of the battery and motor compartments.
However, for small motive devices, providing an integral housing complete with sealing of the battery and motor compartment has proved difficult for users to easily access the battery and motor compartment. The only alternative to a strong seal was unacceptable as a weaker seal would cause the taking of the device to depth to result in cyclical pressure leakage. Where the device is used in salt water, even the slightest leakage can be disastrous.
Seals achieve their integrity by resilient sealing force and area. Both force and area contribute to the necessity for high force of replacement and removal. In a prior underwater motive device, air pressure and a pump were utilized to provide internal assist pressure to unseal the battery and motive compartments. Battery exchange required some setup and interconnectivity time.
Design of underwater motive devices generally allow sealing to be accomplished most effectively during manufacturing and for manufactured components which will not thereafter be disturbed. Any time that a user access can be obtained, the ability to provide factory sealing is impaired. It has been previously difficult to provide user access without a statistical chance of breach of sealing.
Another goal for underwater motive devices is to insure as much as practical that the user is ready to power the device. The provision of an operation switch which is difficult to operate in order to prevent inadvertent operation is generally disadvantageous. Where the user needs frequent starting and stopping, the extra time spent fumbling with an “out of the way” switch will severely reduce the utility of the device. Conversely, the prominence of the switch can contribute to inadvertent actuation.
When stored in the powered, battery connected condition, inadvertent activation can deplete the battery. During use, inadvertent activation can cause the device to go out of a user's control.
What is needed is an underwater motive device which enables easy access to battery change out without diminishing the integrity of the sealed components. Battery change out should be able to be accomplished with ease, and by persons having limited strength. The needed underwater motive device should have a switching system which is handy yet contains safeguards against inadvertent activation and loss of control. Finally, a device is needed which can include factory sealing of most components with minimum sealing breach by the user.